As braking control devices for such a vehicle, in the prior art, patent documents 1 and 2 describe examples of braking control devices. In such braking control devices, the starting timing for the assist control is set without using a sensor that directly detects the depression force applied to a brake pedal by a driver. An example of such a sensor is a pressure sensor that detects a master cylinder pressure.
More specifically, in the above braking control device, an estimated vehicle body speed of the vehicle is calculated based on a detection signal from a wheel speed sensor arranged on the vehicle, and an estimated vehicle body deceleration of the vehicle is calculated based on the estimated vehicle body speed. Further, the braking control device calculates a slip rate of a wheel. In a state in which the driver operates the brake pedal, if the calculated estimated vehicle body deceleration is greater than or equal to a preset first emergency braking determination value and a calculated slip rate of a wheel exceeds a preset second emergency braking determination value, it is determined that the current operation of the brake pedal is an emergency braking operation. This starts an assist control. The assist control is also referred to as “brake assist control (BA control)”.
Instead of using the slip rate of a wheel, the vehicle body deceleration (also referred to as “G sensor value”) may be calculated based on a detection signal from a vehicle body acceleration sensor arranged in the vehicle, and the G sensor value may be used to determine whether the current brake pedal operation is an emergency braking operation.